Manufacture of steam-boiler stay bolts



1 192 7 May 7 A. F. PITKIN MANUFACTURE OF STEAM BOILER STAY BOLTS 2 Sheets-Sheet 1 Filed July 19. 1922 FIG. 1

WITNESSES May 1927 A. F. PITKIN MANUFACTURE OF STEAM BOILER STAY BOLTS Filed July 19. 1922 2 Sheets-Sheet 2 FIG. 7

Patented May 10, 1927.

UNITED STATES *PAT-ENT OFFICE.

MANUFACTURE OF STEAM-BOILER STAY BOLTS.

Applicationflled July 19, 1922. Serial No. 576,027.

My invention relates to steam, boiler stay bolts of the articulated or so-eal ed flexible type, and its object is to rovide a means and method whereby stay bolts of such type, having a socketed end or ends, may be inexpensively H'Ififlllftl-Ctlll'ttl, of sections sufficiently strong tosafely resist thestrains imposed upon them in their pressure. upon inner and outer sheets of steam boilers.

'lhe in'iproveluent clain'ied is hereinafter fully set forth. I I l in the acron'ipanying drawings: Figure l is a view, in elevation, of one section of an impressioned die block adapted to the practice of my invention, with the socket portion of the material operated on shown in section at the conclusion of each operation; Fig. 3, a similar view of a plunger die block, with portions of the plungers shown'in section; Figs. 3, 4' and 5, longitudinal central sections through the socket end of the forging, at the conclusions of the first, second, and third operations respectively; Fig. (3, a similar scition showing the staybolt articulated to a ball member by which it is to be connected to a boiler sheet; and, Fig.7, a view, in perspective, illustrating the relation of the im pressioned and the plunger die blocks.

For the practice of my invention, which is herein exemplified as applied in the manufacture of articulatedst-ay bolts having a socket on one end only, although it is equally and similarly applicable in that of stay bolts having a socket on each end, I provide an impressioned die block which comprises two ounterpart sections, A and A, in the meeting faces of which there are formed three impressions or recesses, a, b and (3,. the rear portions of which, when the counterparts are brought into contact, are of cylindrical section, corresponding to that of thebody of the bolt which is to be manufactured. The adjoining portions, a, I), and c, of the impressions, are of greater diameter, and of I section corresponding to the periphery of the socket which is'to be formed on the bolt, and the extreme front portions, b and c of the impressions, b and c, are of cylindrical .section and of greater diameter than -the portions, 1) and 0.

To operate in connection with the impression die block, there is also provided a plunger die block, B, the face of which carries plungers, at and (F, of diameters corresponding with the portions, a and 71 of the'recesses of the impression die blocks, A,

and a plunger, d, of diameter corresponding substantially with that of the portion, a.

A central projection, d, of smaller diameter,

and an annular groove, d, surrounding the bottom of said projection,- are also formed on the plunger, al For application in connection with the cylindrical end portion, 0 of the impression, as hereinafter described, there is also provided a stout metal ring, A

In the practice of the method of my invention, which is conducted in a forging machine of any suitable known construction, which does not, in and of itself, form part of my present invention, and is not, therefore, herein set forth, one of the sections, as A, of the impression die block, is moved sufficiently away from the other se;-tion, as A, to permit the insertion from the rear, in the impression, a, of a heated bar stock of material of circular or other suitable transverse section, which is allowed to project from the front of the impression, a, sufficiently far that when the sections, A and A, are brought together, and the plunger die block, B, is forced forward by the action of the forging machine, the plunger, d, of said block, will upset or force inwardly the material of the bar stock, so as to fill the space before it in the portion, 0,, of the impression, a, the stock being securely clamped between the sections. v

The end of the stock on which the plunger, d, acts, having been upset to the form shown in the impression, a, in Fig. 1, the bar stock is next inserted in the impression, b, and by the action of the forging machine, is cupped out and brought to the form shown in the portion, 6', of said impression by the plunger, (1, of the plunger die block, B. In the performance of this operation, there is found to be a small flash or protruding peripheral flange, 1, produced on the socket portion, by the metal squeezing out between the die blocks, to remove which the bar stock is placed in the impression, c, in which the ring, A, is inserted, and by another forward movement of the plunger die block, said flash is cut off, thereby completing the formation of the socket.

The stay bolt thus manufactured has a body, 1, and an integral socket, 1, and is ar ticulatecl to the ball, 2", of the plug member by which its socket end is connected to a boiler sheet, by inserting the ball in the socket, and forcing inwardly, around the ball, the outwardly flaring end of the socket,

thereby forming a bearing face on the socket for the ball, and holding the ball in the socket, as shown in Fig. 6. The socket is preferably made of such depths as to present a. space, 1, withinit between the ball and the socket, which allows a limited range of relative longitudinal movement, as set forth in an application for Letters Patent filed by me under date of October 22, 1921, Serial No. 509,551. The exterior surface of the socket is also caused to be essentially cylindrical, and concentric with the axial line of the body, 1, of the stay bolt thereby providing a bearing socket, 1, which is of greater thickness at its outer end than on the remainder of its wall, and, by being so thickened,'is strengthened to such an extent as to effectually resist any tendency for the bolt to be pulled out of the socket, when in service, by the turning outwardly of the end portion, under strain.

I claim as my invention, and desire to secure by Letters Patent:

The method of forming stay a socketat one end for the reception of the rounded head of a companion member, which comprises the following steps: heating a rod to forging temperature; confining the rod in a die cavity, having a constricted portion and an enlarged portion; expanding one end of the rod in the enlarged portion by the pressure of a plunger; confining the rod in a second die cavity; applying pressure to the expanded end of the rod to form a socket therein, with the mouth of said socket thicker than the rest of the wall and curved in cross section; confining the rod in a third die cavity, and cutting oii' any fin formed around the thickened mouth of the socket.

ARTHUR F. PITKIN.

bolts, having 4 

